scholarly journals Analysis of Mediterranean Vegetation Fuel Type Changes Using Multitemporal LiDAR

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 335
Author(s):  
Alba García-Cimarras ◽  
José Antonio Manzanera ◽  
Rubén Valbuena
Keyword(s):  
Vegetation Cover ◽  
Forest Canopy ◽  
Fire Hazard ◽  
Light Availability ◽  
Ecological Factors ◽  
Sun Exposure ◽  
Visual Assessment ◽  
Fuel Type ◽  
Canopy Fuels ◽  
Area Of Interest

Increasing fire size and severity over the last few decades requires new techniques to accurately assess canopy fuel conditions and change over larger areas. This article presents an analysis on vegetation changes by mapping fuel types (FT) based on conditional rules according to the Prometheus classification system, which typifies the vertical profile of vegetation cover for fuel management and ecological purposes. Using multi-temporal LiDAR from the open-access Spanish national surveying program, we selected a 400 ha area of interest, which was surveyed in 2010 and 2016 with scan densities of 0.5 and 2 pulses·m−2, respectively. FTs were determined from the distribution of LiDAR heights over an area, using grids with a cell size of 20 × 20 m. To validate the classification method, we used a stratified random sampling without replacement of 15 cells per FT and made an independent visual assessment of FT. The overall accuracy obtained was 79.61% with a Kappa coefficient of 0.76. In addition, the relationships among different stand structures and ecological factors such as topographic aspect and forest vegetation cover types were analyzed. Our classification algorithm revealed that stands lacking understory vegetation usually appeared in shady slopes, which were mainly covered by beech stands, whereas sunny areas were preferentially covered by oak stands, where the understory reached greater height thanks to more light availability. Our analysis on FT changes during that 6 year time span revealed potentially hazardous transitions from cleared forests towards a vertical continuum of canopy fuels, where wildfire events would potentially reach tree crowns, especially in oak forests and southern slopes with higher sun exposure for lower fuel moistures and increased flammability. Accurate methods to characterize forest canopy fuels and change over time can help direct forest management activities to priority areas with greater fire hazard. Multi-date canopy fuel information indicated that while some forest types experienced a growth of the shrub layer, others presented an understory decrease. On the other hand, loss of understory was more frequently detected in beech stands; thus, those forests place lower risk of wildfire spread. Our approach was developed using low-density and publicly available datasets and was based on direct canopy fuel measurements from multi-return LiDAR data that can be accurately translated and mapped according to standard fuel type categories that are familiar to land managers.

Large-scale mapping of the catenas vegetation in Subarctic tundra

1995 ◽  
pp. 3-21
Author(s):  
S. S. Kholod
Keyword(s):  
Spatial Distribution ◽  
Vegetation Cover ◽  
Large Scale ◽  
Block Diagram ◽  
Abiotic Factors ◽  
Ecological Factors ◽  
Spatial Arrangement ◽  
Geological Time ◽  
Ecological Barriers ◽  
Functional Zones

One of the most difficult tasks in large-scale vegetation mapping is the clarification of mechanisms of the internal integration of vegetation cover territorial units. Traditional way of searching such mechanisms is the study of ecological factors controlling the space heterogeneity of vegetation cover. In essence, this is autecological analysis of vegetation. We propose another way of searching the mechanisms of territorial integration of vegetation. It is connected with intracoenotic interrelation, in particular, with the changing role of edificator synusium in a community along the altitudinal gradient. This way of searching is illustrated in the model-plot in subarctic tundra of Central Chukotka. Our further suggestion concerns the way of depicting these mechanisms on large-scale vegetation map. As a model object we chose the catena, that is the landscape formation including all geomorphjc positions of a slope, joint by the process of moving the material down the slope. The process of peneplanation of a mountain system for a long geological time favours to the levelling the lower (accumulative) parts of slopes. The colonization of these parts of the slope by the vegetation variants, corresponding to the lowest part of catena is the result of peneplanation. Vegetation of this part of catena makes a certain biogeocoenotic work which is the levelling of the small infralandscape limits and of the boundaries in vegetation cover. This process we name as the continualization on catena. In this process the variants of vegetation in the lower part of catena are being broken into separate synusiums. This is the process of decumbation of layers described by V. B. Sochava. Up to the slope the edificator power of the shrub synusiums sharply decreases. Moss and herb synusium have "to seek" the habitats similar to those under the shrub canopy. The competition between the synusium arises resulting in arrangement of a certain spatial assemblage of vegetation cover elements. In such assemblage the position of each element is determined by both biotic (interrelation with other coenotic elements) and abiotic (presence of appropriate habitats) factors. Taking into account the biogeocoenotic character of the process of continualization on catena we name such spatial assemblage an exolutionary-biogeocoenotic series. The space within each evolutionary-biogeocoenotic series is divided by ecological barriers into some functional zones. In each of the such zones the struggle between synusiums has its individual expression and direction. In the start zone of catena (extensive pediment) the interrelations of synusiums and layers control the mutual spatial arrangement of these elements at the largest extent. Here, as a rule, there predominate edificator synusiums of low and dwarfshrubs. In the first order limit zone (the bend of pediment to the above part of the slope) one-species herb and moss synusiums, oftenly substituting each other in similar habitats, get prevalence. In the zone of active colonization of slope (denudation slope) the coenotic factor has the least role in the spatial distribution of the vegetation cover elements. In particular, phytocoenotic interactions take place only within separate microcoenoses of herbs, mosses and lichens. In the zone of the attenuation of continualization process (the upper most parts of slope, crests) phytocoenotic interactions are almost absent and the spatial distribution of vegetation cover elements depends exclusively on the abiotic factors. The principal scheme of the distribution of vegetation cover elements and the disposition of functional zones on catena are shown on block-diagram (fig. 1).

scholarly journals Monitoring scrub weed change in the Canterbury region using satellite imagery

2007 ◽  
Vol 60 ◽  
pp. 137-140 ◽  
Author(s):  
J.D. Shepherd ◽  
J.R. Dymond ◽  
J.R.I. Cuff
Keyword(s):  
Satellite Imagery ◽  
Vegetation Cover ◽  
Satellite Image ◽  
Visual Assessment ◽  
Woody Vegetation ◽  
Spatial Change ◽  
Valid Data ◽  
Woody Cover ◽  
Landsat Satellite ◽  
Thematic Data

The spatial change of woody vegetation in the Canterbury region was automatically mapped between 1990 and 2001 using Landsat satellite image mosaics The intersection of valid data from these mosaics gave coverage of 84 of the Canterbury region Changes in woody cover greater than 5 ha were identified Of the 5 ha areas of woody change only those that were likely to have been a scrub change were selected using ancillary thematic data for current vegetation cover (eg afforestation and deforestation were excluded) This resulted in 2466 polygons of potential scrub change These polygons were rapidly checked by visual assessment of the satellite imagery and assigned to exotic or indigenous scrub change categories Between 1990 and 2001 the total scrub weed area in the Canterbury region increased by 3600 400 ha and indigenous scrub increased by 2300 400 ha

Are resources allocated differently to symbiosis and reproduction in Geranium sylvaticum under different light conditions?

2004 ◽  
Vol 82 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Jarkko Korhonen ◽  
Minna-Maarit Kytöviita ◽  
Pirkko Siikamäki
Keyword(s):  
Resource Allocation ◽  
Forest Canopy ◽  
Light Availability ◽  
Growing Season ◽  
High Light ◽  
Mycorrhizal Colonization ◽  
Fungal Colonization ◽  
Low Light ◽  
Light Levels ◽  
Dark Septate Fungi

Light levels under the forest canopy are low and generally limit plant photosynthetic gains. We hypothesized that in low-light habitats, plant photosynthate acquisition is too low to allow the same magnitude of resource allocation to symbiosis and reproduction as in high-light habitats. We tested this hypothesis in a field study where Geranium sylvaticum L. plants were collected on three occasions during the growing season from shade and light habitats. In addition, we investigated the relationship between mycorrhizal colonization level and soil nutrient levels in shade and high-light habitats over a growing season. We found that light availability affects resource allocation in G. sylvaticum. Plants were intensively colonized with both arbuscular mycorrhizal and dark septate fungi, and the colonization intensities of these two different groups of fungi correlated positively with each other. In comparison with high-light meadows, mycorrhizal colonization levels were as high or higher in low-light forest habitats, but plants produced fewer flowers. This indicates that allocation to symbiosis was of higher priority than allocation to reproduction in low light. Seed size was not affected by light levels and did not correlate with fungal colonization levels. We found no relationship between fungal colonization levels and soil characteristics.Key words: arbuscular mycorrhiza, dark septate fungi, Geranium sylvaticum, reproduction, shade.

scholarly journals Asynchronous Amazon forest canopy phenology indicates adaptation to both water and light availability

2014 ◽  
Vol 9 (12) ◽  
pp. 124021 ◽  
Author(s):  
Matthew O Jones ◽  
John S Kimball ◽  
Ramakrishna R Nemani
Keyword(s):  
Forest Canopy ◽  
Light Availability ◽  
Amazon Forest

Middle-scale mapping of vegetation cover of the Moscow District at the ecological-dynamic basis

1996 ◽  
pp. 3-15
Author(s):  
G. N. Ogureeva ◽  
I. M. Miklyaeva ◽  
E. G. Suslоva ◽  
L. V. Shvergunova
Keyword(s):  
Vegetation Cover ◽  
Plant Cover ◽  
Ecological Factors ◽  
Anthropogenic Factors ◽  
Ecological Stability ◽  
Vegetation Map ◽  
Human Environment ◽  
Ecological Dynamic ◽  
Vegetation Class ◽  
Dynamic Series

Middle-scale vegetation map shows the most important botanical-geographic reguliarities of plant cover depending on the environmental conditions of the territory. Legend divisions reflect the typological differentiation of vegetation cover (fig. 1). The higher rank units are: type of vegetation, class of formations, group of formations, formation. Class of associations and group of associations are adopted as the main mapping units. Forest vegetation is classified and analyzed in terms of the ecological-dynamic concept by V. B. Sochava (1968, 1979). According to this concept forest association is considered to be a part of dynamic system (epiassociation), integrating both the climax community and its modifications which arise in the course of spontaneous or anthropogenic succession. In the case of mesic meadows the method of ecological-dynamic series is used. The series are grouped according to leading ecological factors (soil fertility and humidity) or anthropogenic factors (grazing and haymaking). Middle-scale vegetation map of the Moscow District based on the ecological-dynamic principle is highly informative. It reflects the coenotic diversity, botanical-geographic reguliarities, typological diversity of climax and secondary communities of forests, mesic meadows, mires taking into account the floristic, phytocoenotic, ecological and geographic criteria. The map shows modern status of and trends in vegetation dynamics depending on anthropogenic impact. The vegetation map of such kind can be used for solving the ecological problems: monitoring, supporting the ecological stability, presevation and improvement of a human environment.

Fusion of LiDAR and imagery for estimating forest canopy fuels

2010 ◽  
Vol 114 (4) ◽  
pp. 725-737 ◽  
Author(s):  
Todd L. Erdody ◽  
L. Monika Moskal
Keyword(s):  
Forest Canopy ◽  
Canopy Fuels

scholarly journals Lidar Processing for Defining Sinkhole Characteristics under Dense Forest Cover: A Case Study in the Dinaric Mountains

2014 ◽  
Vol XL-7 ◽  
pp. 113-118 ◽  
Author(s):  
M. Kobal ◽  
I. Bertoncelj ◽  
F, Pirotti ◽  
L. Kutnar
Keyword(s):  
Forest Canopy ◽  
Forest Cover ◽  
Traditional Approach ◽  
Ground Truth ◽  
Visual Assessment ◽  
Forest Tree ◽  
Tree Canopy ◽  
Karst Terrain ◽  
Ground Truth Data ◽  
Dense Forest

The traditional approach for defining sinkholes characteristics is based on topographic maps and air photographs with derived digital terrain models. This method is sometimes not accurate, requiring costly, time consuming and potentially dangerous fieldwork. Investigations have shown that airborne scanning laser data (lidar) is useful in detection of karst depressions due to the high density of ground points that can be obtained. This is especially important under dense forest canopy, where classical photogrammetric methods do not allow ground points to be measured. The objective of this work was to map and determine geomorphometric characteristics of a large number of sinkholes located in a diverse karst terrain under a dense forest tree-canopy using lidar data. <br><br> We tested an algorithm described in previous literature which uses only information from the DTM. It is based on water flow simulations on a surface (DTM) and incorporates four phases: (i) watershed delineation, (ii) confining of sinkholes, (iii) confining of higher rank sinkholes and (iv) extraction of non-karstic sinkholes. Sinkholes were confined by effluent level with cells below the effluent level designated as part of the sinkhole. In the third step sinkholes were ranked according to their location and size – first rank sinkholes are the smallest and are located within a larger sinkhole. <br><br> Results are that the sinkhole fraction of 1st, 2nd, 3rd, 4th and 5th rank in the study area was 3.25 %, 4.26 %, 5.68 %, 3.65 % and 3.14 %, respectively. Sinkhole distribution shows a peculiar directionality in their spatial distribution, which seems to be significantly towards a northwest – southeast direction. It was not possible to compare results with ground-truth data due to very low accessibility, nevertheless a statistical and visual assessment of the results shows that lidar is a very effective technique to model sinkholes under dense canopy.

scholarly journals Background Insect Herbivory in Riparian Poplar Forests: the Role of Local, Landscape, and Regional Factors

2021 ◽  
Author(s):  
Binli Wang ◽  
Chengming Tian ◽  
Yingmei Liang ◽  
Dongping Liu
Keyword(s):  
Forest Management ◽  
Vegetation Cover ◽  
North China ◽  
Control Strategies ◽  
Insect Herbivory ◽  
Ecological Factors ◽  
Tree Height ◽  
Riparian Forests ◽  
Tree Size ◽  
The Impact

Abstract BackgroundForest management and landscape structure have long been considered as the main drivers of insect herbivory in forest landscapes, but relatively little is known about how ecological factors acting at local, landscape and regional scales shape background insect herbivory under natural conditions. Here, 90 primeval and managed poplar stands were sampled in riparian forests along the rivers in the Eastern part and the Western part of North China. We measured defoliation intensity of insect herbivores within forest stands in transects at near, intermediate and far distance from the rivers. We assessed the effects of region, landscape isolation, forest management, stand position, vegetation cover, and tree size on defoliation intensity. We also explored indirect effects of region and forest management on insect herbivory via changes in stand-level tree size and vegetation cover. ResultsDefoliation intensity increased with landscape-scale forest isolation and decreased with distance from forest stand to the river regardless of stand type. Defoliation intensity was higher in primeval stands than in managed poplar stands, but this difference only significant in the Eastern part of North China. Tree height varied among two regions and between primeval and managed stands. Defoliation intensity was strongly correlated with tree height and vegetation cover. But the effects of region and forest management on defoliation intensity were only partly explained by tree size and vegetation cover. ConclusionsThese results indicate that background insect herbivory can be driven by ecological factors at different scales and offer an insight into the impact of man-made changes along a gradient of landscape isolation in forest ecosystems. Our findings provide a multi-scale perspective to improve potential control strategies and risk assessment of insect damage on riparian forests in real-world situations.

scholarly journals Estimación de la distribución vertical de combustibles finos del dosel de copas en masas de Pinus sylvestris empleando datos LiDAR de baja densidad

2019 ◽  
pp. 1 ◽  
Author(s):  
L. A. Fidalgo-González ◽  
S. Arellano-Pérez ◽  
J. G. Álvarez-González ◽  
F. Castedo-Dorado ◽  
A. D. Ruiz-González ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Fire Hazard ◽  
National Forest Inventory ◽  
Fuel Load ◽  
Crown Fire ◽  
Cross Model ◽  
Canopy Fuels ◽  
Structural Variables ◽  
Fire Initiation ◽  
Using Data

<p>Canopy fuel load, canopy bulk density and canopy base height are structural variables used to predict crown fire initiation and spread. Direct measurement of these variables is not functional, and they are usually estimated indirectly by modelling. Advances in fire behaviour modelling require accurate and landscape scale estimates of the complete vertical distribution of canopy fuels. The goal of the present study is to model the vertical profile of available canopy fuels in Scots pine stands by using data from the Spanish national forest inventory and low-density LiDAR data (0.5 first returns  m<sup>–2</sup>) provided by Spanish PNOA project (Plan Nacional de Ortofotografía Aérea). In a first step, the vertical distribution of the canopy fuel load was modelled using the Weibull probability density function. In a second step, a system of models was fitted to relate the canopy variables to Lidar-derived metrics. Models were fitted simultaneously to compensate the effects of the inherent cross-model correlation between errors. Heteroscedasticity was also analyzed, but correction in the fitting process was not necessary. The estimated canopy fuel load profiles from LiDAR-derived metrics explained 41% of the variation in canopy fuel load in the analysed plots. The proposed models can be used to assess the effectiveness of different forest management alternatives for reducing crown fire hazard.</p>

scholarly journals Assessing the importance of genetic and ecological factors for the occurrence of patchy flowering in Posidonia oceanica

2015 ◽  
Author(s):  
Marlene Jahnke ◽  
Jordi F Pagès ◽  
Teresa Alcoverro ◽  
Paul S Lavery ◽  
Kathryn M McMahon ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Kin Selection ◽  
Genetic Factors ◽  
Light Availability ◽  
Ecological Factors ◽  
Posidonia Oceanica ◽  
Positive Interaction ◽  
Vegetative Tissue ◽  
Individual Fitness ◽  
Tissue Production

The occurrence of sexual reproduction and flowering synchronization of angiosperms has been widely studied and may be induced by external or internal cues. Although factors such as predator satiation and pollination efficiency may explain why synchronization can increase individual fitness, the actual mechanisms of synchronization are obscure for the majority of plant species. In this study we aimed to assess the importance of ecological and genetic factors in shaping flowering heterogeneity of Posidonia oceanica at the small spatial scale (metres), where shoots and patches were subjected to similar levels of the major potential external drivers such as temperature and light availability. We assessed four external ecological factors (vegetative tissue production, leaf nitrogen and carbon content and herbivory) and three genetic factors (heterozygosity, relatedness and clonality). We sampled six patches with contrasting flower abundances at three different localities and analysed whether spatial heterogeneity in the abundance of flowers was due to (1) clone identity and clone synchronization, (2) variation in nutrient availability per individual, potentially caused by spatial heterogeneity in herbivory rates (or nutrient re-location via clonal integration) or (3) kin selection and sibling synchronization. Moreover, we also investigated if levels of genetic diversity, specifically observed heterozygosity as a proxy for individual fitness, differ between flowering patches and patches with low flower abundance. We show that genetic factors play a major role: Both internal relatedness and heterozygosity have a significant positive interaction with the abundance of flowers. Moreover, vegetative tissue production and the number of clones per patch were negatively correlated with the number of flowers, although at a low level of significance. Sharing of clones within localities was almost exclusively among patches with high flower abundance and patches with low flower abundance, respectively. Our results support the kin selection hypothesis and indirectly the resource-budget hypothesis, as well as an interaction between genetic factors and environmental factors as cause for the observed heterogeneous flowering patterns. Overall, the results shed new light onto the mechanisms explaining flowering synchronization in P. oceanica.

Sign in / Sign up

Export Citation Format

Share Document